Conventional hole-making systems used to drill underground boreholes in the oil and gas industry are all based on hydro-mechanical drilling techniques using rotating drill bits and drilling fluid to evacuate rock cuttings. Most of these systems require heavy, bulky and expensive surface equipment—either a complete drilling rig, or a complete coiled tubing drilling system.
New ways of making holes in underground formations have been investigated recently which are not based on mechanical drilling systems. For example, using a laser beam to destroy the rock, or using electrical sparks, or even using high pressure hydraulic jetting with or without solid particles. However, none of these systems have been used for commercial applications such as wells for oil and gas production. A number of technical issues exist with these principles which, as of today, have not been overcome.
This invention is based on the use of a gas cutting system. The terms ‘gas cutting’, ‘gas torch’ and other related terminology are used to denote a thermal cutting system in which a jet of hot gas is provided from a torch head for removal of solid material. Common forms of gas cutting technology include oxy-fuel systems in which a fuel and an oxidizing agent are combusted at a burner head to provide a very hot flame (e.g. oxy-acetylene systems); and plasma or plasma arc systems in which a plasma is initiated in a jet of a gas (e.g. argon, nitrogen, oxygen, etc.) by RF stimulation and this is used to remove material.
The aim of the invention is to provide a plasma torch based system that can make long holes in underground formations, in presence of various fluids (oil based mud, water based mud, formation fluids, etc. . . . ), and at temperature and high pressure conditions met at depth exceeding 1000 meters. The system will not only be capable of making holes, but will also eliminate rock particles and will carry its own source of energy for making the hole. The system can be used in particular to make long lateral holes from existing wells.